1. Field of the Invention
The present invention relates to protective devices and, in particular to devices for preventing the spillage of concrete residues from the chutes of vehicle mounted concrete mixers.
2. Prior Art
Vehicle mounted cement mixers are an important part of virtually all construction projects. The mixers are loaded at a fixed base then, while in transit to the job site, mix the loaded ingredients. Upon arrival at the site, the mix is ready for application.
The most common method of discharging the mix is by way of a vehicle mounted discharge chute which is hinged and which is moveable to the exact location for placement of the mix. The mix is then flowed, pushed, scooped, or raked into a form where it then hardens, with or without further processing.
In the past, operation of concrete mixers employed to deliver concrete mix to construction sites have used various techniques to minimize the spillage of concrete residues during return to the mixer's fixed base.
Sometimes, the residue is washed out of the chute onto the ground in the vicinity of the site. This technique suffers from the obvious drawback that concrete residues are left behind, remaining at the washout site contaminating the environment and, at best, leaving behind a hardened, "poisoned" patch which cannot support vegetation.
The practice of washing out the chute has been proscribed by local ordinances in many communities and is considered, even when not specifically outlawed, to be an unwelcome and unsatisfactory practice.
Another technique sometimes employed is the rinsing of the chute back into the mixer tank. Although preferable to washing out onto surface soil, the technique suffers from the fact that the wash water dilutes the contents of the tank, eventually making the remainder of the load unsuitable for further use.
Of all the prior techniques, the one which is the most objectionable is to attempt to forego any washout by merely leaving the residue resting precariously in the discharge chute while the mixer is returning to its final base. The residue left in the chute is susceptible to being dislodged and then falling onto the pavement.
It is of course illegal to drop such items onto the pavement at any time. Moreover, concrete residues which have fully hardened are hazardous projectiles which all too often create damage to property in the form of broken windshields, dented or marred sheet metal, and, even worse, injury and death to persons who are struck by the flying debris.
Concrete particles as large as 4 kg. are known to form regularly in discharge chutes which have not been washed down prior to returning to streets and highways.
In addition to the risks of actual contact, drivers who are behind a truck from which residue falls will frequently make violent and unpredictable evasive maneuvers which, although successful in avoiding the concrete residue itself, result in a more violent impact with another vehicle or a stationary object. Sometimes, multiple car accidents involving numerous injuries and even death are the result.
In some regions, mixer drivers are subject to misdemeanor negligence charges for dropping mixer chute residues on public roads.
Accordingly, a need exists for an apparatus which can reliably contain concrete mixer chute residues and prevent them, when dislodged, from finding their way onto the streets and highways.